Thermally controlled grinder head



Feb. 3, 1942. R .GARRlsON ETAL 2,271,637'

THERMALLY coNTRoLLED GRINDER HEAD y Filed Feb. 2. 1938.

'7 Sheets-Sheet 2 fllll Feb.v 3,1942. RIP. GARRlsoN 4l-:TLv 2,271,637

THERMALLY CONTROLLED GRINDER HEAD Filed Feb. 2, 1958 'rsneets-sneeta 59i 1Q I Fell 3, 1942 VF. GARRlsoNET AL 2,271,637

THERMALLY CONTROLLED GRINDER HEAD Fell 3, 1942- R. P. GARRlsoN ETAL2,271,637

- THERMLLY CONTROLLED GRINDER HEAD Filed Feb. 2, 1938 '7 Sheets-Sheet 5fill wvankw attenua' Feb. 3, 1942.

Rl P. GARRlsoN s1-AL THERMALLY CONTROLLD GRINDER HEADv Filed Feb. 2.1938 7 Sheets-Sheet 6 llllunw llllllllllllllllluu. llll'llllllllllllllll Lul um l

Feb. 3, 1942.

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bw V lrHl k wm mm Q l machine tool wherein work pieces and tools are Theconstruction herein illustrated is particu- Patentecl Feba, 19'42 Y i tl,

UNITED STATES l PATENT OFFICE;

THERMALLY CONTROLLED GRINDER HEAD mips r. Garrison ma John n. Garrison,'MAY 51 t Dayton, Ohio '22 19 l I Application-February 2, 193s, semi No.isssss R 16 Claims. (Cl. 5142,81)

This invention comprises a method-and appain a position coincident withthev particular ratus for controlling stresses, strains andvarianormal",running temperature of the machine, tions of position inmachine tools and machine and are maintained in that position bothduring toolparts developed incident to temperature fiucthe operation ofthe machine and'when the matuations and resultant contraction andexpanchine -is-idle whereby the machine parts will not sion as producedby operation of the machine be subjected to contraction and `expansionretool and changes in atmospheric temperatures. sulting from temperaturechange, and their po- The invention is particularly applicable to anysition ailected thereby. a

relatively positioned and the work piece and tool larly adoptedy t0centering and h01dingfbeve1d relatively moved for affecting a desiredresult in gears for performing machining, refinishing, the work piece,although it is equally applicable boring, or grinding operationsthereon, v It is unto machines and apparatus of all kinds. derstood,however, that the present device is It might seem that the natural' andlogical adaptable for holding articles other than gearsv manner ofcounteracting the effect of heat gen- 15 and for all manner ofmachining, grinding, erated during,A operation of the machine wouldboring and other operations. As Well as embodybe by air cooling thepart, or by circulating ing means for controlling the temperature ofthel other cooling medium by which the generated machine, the machine isso constructed and arheat would be dissipated. However, cooling ofranged that work may be supported without the bearing and frame merelycauses contrac- 20 overhang. and with the center of the work piece tionand tightness of the bearing with a consepractically in line with thefront work support quentdevelopment of more heat, necessitating end.Also, it is so constructed and arranged that an increased amount ofcooling. Use of the coolthe work may be loaded into the chuck from aingprinciple is likewise conducive to undesirable lateral directionbetweenl the supporting.y bearsweating.` The present system overcomes'25 ings, and means are provided forvprotecting an these diilicultiesand provides for uniform operoperator from contact with moving parts.ating conditions by heating the bearingMframe, `One object of theinvention is to simplify the and the spindle, and other parts incontactdiconstruction as well as the means and mode -of rectly orindirectly with the bearing and fr e, operation of a device'as disclosedherein whereby to a degree at least'equal'to the highest tem er-v 30such devices may not only be economically manature likely to bedeveloped during operation, ufactured, but will be more eiiicient andaccurate -and providing automatic control means for in use, adaptable toa wide variety of work pieces, maintaining this as a uniform workingtemperof relatively few parts andl unlikely to get out ature bycirculation of heating medium and the of repair. a

employment of suitable heaters therefor under. Another object of theinvention is to provide thermostatic control. method and apparatus fortemperature control In vmachines as ordinarily constructed, bearinmachines of the character disclosed which is ings are fitted at atemperature far below that simple yet highly efilcient 'in operation,and which is attained during the operation of the wherein the apparatusembodies controlmeans machine, and arelikewise set up in theirA sup- 40adaptable to maintain the apparatus at any preports at the same lowtemperature with the re` selected normal temperature. suit that thesupports and bearings bothv attain- Another object of the invention isto provide a considerably higher temperature during opermethod andapparatus for temperature control ation of the machine over a period oftime than whereby stresses and strains, and Yvariations in when thebearings were fitted. As` a result of 45 position of machine partsdeveloped incident to this assembly practice, when the machine is putltemperature change from any source and resultinto operation therel is adefinite change in posiant contraction and expansion are eliminated.

tion in the machine and parts due to expansion A'further object of theinvention is to provide and contraction,`which isy directly proportionalmethod and apparatusl for temperature ,control to change in temperature,and which directly which will eliminate any delay incident to amaailects machine alignment andthe work result chine being successivelyin and out of a desired produced by the rmachine. In accordance withoperating condition.

this invention, vital parts of a machine are man- A further object ofthe invention is to increase v ufactured and assembled and the bearingsthe lifeof bearings and the journals operating therefor ii-tted o'r runin while the various ma- 55 therein by providingl for a closer originalfit bea chine parts are at a temperature at least equal tween thebearings and journals, and maintainto the temperature attained yby the.machine ing such fit substantially constant so far as Vit parts as aresult of operation of the machine. may be affected by `contraction andexpansion.

Thus, thev machine and important parts are A further object of theinvention is to provide manufactured `and assembled'in a condition and"60 for maintenance of the same clearance between bearings` 'andVasociated journals, except such variations as maybe induced by wear, atall times and regardless of whether the machine tool is in or out ofoperation.

' A further object of the invention is to provide v for.mai ntenance oithe 4lubricant at a constant temperature and thuseliminate any rise intemperature on initial operation of the machine tool due vto thelubricant being at a relatively high viscosity and rubbing over itself.'

A further object ofthe invention-is to provide` f other parts.

A further object of the invention is to insure uniformity of precisionmethod production by maintaining the operating condition constant.

' A further object of the invention is to provide a machine of thecharacter hereinafter described wherein there is av minimum or nooverhang of-the work piece with respect to its support.

A further object of the invention is to provide fory ease of loading awofrk piece in its support.

A further object of the invention is to provide safety features in the.machine for the protection of the operatorof the tool from moving parts.

A further object of the invention is to provide a machine possessing themeritorious characteristics above mentioned.

With the above primary and other incidental which permits access to thehollow spindle, such door being in open position.

' Like parts are indicated by similar characters of reference throughoutthe several views.

For lillustrative purposes, but with no intent to unduly limit theapplication or scope of the invention, the assembly herein shown anddescribed is especially designed for grinding the rear, side and bore ofatypical automotive driving gear of the spiral bevel type. I

Referring to the, drawings, and particularly Fig. 1 thereof, there isshown a work holder or chuck including a base portion I for uprightsupporting members 2 and 3 in which suitable bearings 4 and 5are-respectively mounted, and in which bearings a spindlef rotates. Theupright 2 is provided with l. bearing cover plate 'I and a thrust ringl, vthe thrust ring being held `in position by bolts 9. Both the frontand rear bearings have adjusting nuts III, and the upright 3 is shown ashaving a bearing liner II, with the spindle 6 mounted to float in thebearing 5.

'The portion of the spindle' 6 extending forwardly of theupright I andbearing 5 is hollow to form a holder in which the gear or other workpiece `is mounted. The hollow portion of the spindle 6 has a lateralopening permitting access to the interior of the spindle, and a door 6a,Fig.

9, having a suitable latch is hinged to the spindle and rotatestherewith covering the opening in the spindle side walls and barringaccess to thednterior of the spindle when closed. Suchdoor objects inview, as will more fully appear in the-v specification, the inventionconsists of the features and methods of construction, the parts andcombinations thereof, and the mode of opera` tion, or their equivalents,as hereinafter de- A Y scribedand set forth in the claims.

Referring to the accompanying drawings wherein is found the preferredbut obviously not necessarily the only form of embodiment of theinvention,

Fig..1-is a view, partly in elevation and partly in section, showing aworkholder or chuck having temperature control means applied thereto inaccordance with the idea disclosed by this r invention..

Fig. 2 is a top plan view of the work holder or chuck shown in Fig. 1.

Fig'. 3 is an end elevation of the work holder or chuck shown. in Figs.1 and 2, and showing more fully the temperature control means.

Fig. 4 is afront elevation showing the regulating and indicatingmechanism for the temperature control means.

Fig. 5 is a rear elevation of the regulating and indicating mechanismshown in Fig. 4. i

`Fig. 6 is a top planAview of an'entire machine tool, including the workholder or chuck, the tool for operating on the work, and the holding.means therefor.

Fig. 7 is an elevation of 'a modified form of the invention showing theheating principle and the apparatus therefor as applied to the baseofthe machine. A

also serves to properly'balance the spindle. An interchangeable chuck I2in the forward end of the interior of the hollow spindle 6 is secured tothe spindle by bolts Il and includes locating studs I4, theinterchangeable chuck being fully disclosed in the copending applicationof John Russell Garrison, Serial No. 302,385, filed November 11939. Inorder that a work piece inserted into the hollow spindle 6 may be'guided into proper position relativelyto the chuck I2', a loading-tubeI5 is disposed within the hollow spindle and in advance of the chuck l2,the loading tube being inclined in a direction toward the chuck so as toguide the work piece into .proper engagement therewith.

Within the hollow spindle 6, and to the rear -fof the chuck I2 andloading tube I5, is a-support for a pinion gear shaft which takes theform of -an L-shaped member Ii having one leg secured to the innersurface of the hollow spindle 6 las by bolts `I`| and having the shaftsupporting leg I8 extending toward the center of the hollow spindle 6.The leg I8 terminates in such position that the free end of the gearshaft maybe readily engaged by a center bar Il having a replaceablecenter 20 in its forward. end and movable longitudinally or endwise inbushings 2I within the small end of vthe spindle 6 under the action of acompression spring 22 bearingA against a collar 23 rigidly secured tothe center bar for yieldingly engaging the free end of a gear shaft andyieldlnglyvforcing the gear into engagement with the interchangeablechuck I2. The leg I8 may be made adjustable as to height if desired.

The spindle 6 is rotated in its bearings 4 and 5 to rotate the gearrelative to a tool supported at the end of the spindle by an overrunningclutch 25 including driving rollers 2B and a pulley 21 over which a beltfrom a' motor or the like passes, or by means of a hand wheel 28 rigidlymounted on the spindle 8 by bolts 30. The spring 22 is held in place bya cover casting 29 and screws 22a. To stop rotation of the spindle B, abrake to one end of va shaft 34 extending transversely of the base Ibeneath the spindle 6 and the shaft 34 has rigidly securedto itsopposite end a pinion 35 which coacts with a rack 36, Fig. 5, forming apart of a rack bar 31 on the rearward side of the base I and mounted insuitable supports 33 for endwise or longitudinal movement. Rigidlysecured to one free end of the rack Ibar 31 is a the flow of lubricant.Sight glasses are`disposed in the lubricant conveying lines, and meansare provided for venting the lines. A hand or automatic valve may bevprovided in the overflow line 48a from the illter 48 to the header 60to break the syphonic action when the device is not inv use so as toprevent the lubricant in the filter from vsiphoning out into the header.

The center bar lI3 is hollow to receive a supply of lubricant introducedunder .pressure through fitting 24 at the end of the bar, the

'lubricant entering a chamber 6I between the bushings 2| by way of aport 62. The chamber forked arm4 39, the forked end of which looselyengages a collar 46 secured to the center bar I9.

Thus, when the hand lever 33 is moved to the left, Figs. 4 and 5,torotate the shaft 34. the ,rack

bar 31 is moved longitudinally or endwise by the pinion 35 and rack 36and moves the center bar I9 `longitudinally or endwise against theresistance 6I holds a supply of lubricant which is conveyed to thebearing surfaces of the center bar I3 and bushings 2 i by thelongitudinal or endwise movement of the -center bar.

The uprights 2 and 3 include jackets 63 and 64 which surround the'bearings 4 and 5 and the spindle'6 at its4 points of rest in thebearings for the circulation of a liquid, for example, water. HeatersIUI and |02, one for each bearling, preferably electric, are disposedinthe botof the compression spring 22 through the connection between therack ,bar and the center bar I9 by means of the forked arm 39 and collar40. To vary the extent of `movement of the center bar I 3 so as toaccommodate gear shafts of different lengths, the collar 40 may beadjusted along the length of the bar.

Referring to Figs. 1 and 2, the chuck I2 is within the vertical plane ofthe frontspindle bearing 4. Thus, there is no overhanging of the gearwith respect to `thebearing support for the chuck which lends to freedomfrom chatter and insures a minimum of run-out error as compared tochucks where there is a substantial overhang of the'chucked-gear. Whereoverhang is present,

any error in the work head bearings or in mounting the interchangeablechuck is multiplied, and this error might very well be so great as tomake it impossible to achieve the extreme accuracy and ilne finishrequired.

Lubrication is provided for the bearings 4 .and 5 by an oil pump 4I.operated by a projection 42 on lthe spindle v6, which on each rotationstrikes the pump pistonrod 41 and actuates the pump piston. Lubricant isforced from the pump 4I into an oil lter 48, Fig. 4, from which it flowswithout pressure other than the few inches the head of oil in the filteris above the bearings through inlet conduits 43 and 5 0 to the front andrear bearings 4 and 5 respectively. Pump 4I delivers more lubricant thanis needed to the filter 43, and the overilow returns to the supply tankby way of a pipe 48a and an overflow header. I'hus a constant head oflubricant is maintained-in the filter 43.

The inlet conduits v49 and 50 lead to'passages 5I and 52 in the bearingsupports 2 and 3 and communicate with passages 5 4 and 55 in thebearings 4 and 5 which convey the lubricant to eccentrically formed oilgrooves in the bearings 4 and 5.

Such bearings 4'and 5 utilize all the lubricant they require, and excesslubricant not used bythe bearings 4 and 5 leaves the .sight glassesthrough conduits 58- and 53 (Fig. 3) to bearing overflow header 6,0.Used and surplus oil passing through the bearings 4 and'5 (Fig. 1) leave-the bearingsthrough channels 51, 51a and 56,l

tom of each jacket, anda flow circuit is provided through each jacket 63and 64 by means of pipes`65, 66 and 61 having liquid supply reser-'voirs 68 interconnected therewith. thermo-syphonic circulating 'systemis established, with the cooled or cold liquid entering at thebottom ofthe jackets where it is subjected to the heating means,- and lupon beingheated rises in the jackets tov thus establish,a

flow. The liquid reservoirs 68 maintain the flow circuit including thejackets and the pipes 65, 66 and 61 constantly filled, and likewiseserve as av deterrent `on rapid or violent temperature fluctuation ofthe yliquid in the circulating system.

As the liquid becomes heated it rises into the reservoirs 68 anddisplaces a corresponding volpositions of the jackets 63 and 64 havegreater 'exposed areas than the bottoms of the jackets.

Consequently, heat will'be dissipated faster at the tops of the jackets,whereby the temperature of the liquid will be approximately equalthroughout theentire jackets. Thermostatic control means 63,4 one for.each ofthe front and rear bearings, are provided for controllingoperation of the heating -units and thus the temperature of the liquidin the jackets. Suitable air vents prevent 'air pockets forming in thejackets.

-is dissipated to the bearings 4 and 5 and associated parts of themachine and by controlling the temperature of the liquid, thetemperature of the machine parts may be regulated. 'I'hat is, thehighest temperature attained by the machine parts as a result of machineoperation `may be adopted as "normal for' the temperature of the liquidin the Jackets, and that temperature in the machine maintained constantboth during machine operation and when the machine is idle. Such normaltemperature, while higher than room temperatures) is always less thanthetemperature at which the oil film in the bearings 14 and 5 will breakdown.

'I'he provision of heating means as just described makes it possible tomake and set the bearings and bearing lits with the machine parts atrunning temperature, or whatever tempera- Thus, 8.

ture has been adopted as normaL That is. in effect the machine asconcerns the frame, the bearings and spindle assembly may be assembledat a temperature which does not change thereings, with that clearanceremaining uniform through control of the temperature of the parts, whichmakes possible the use of a very thin oil, f

it being known that thin oil has less tendency to rub over itself andproduce friction and heat. It will be noted that the oil passages 5|,52, 54 and 55 through which oil is introduced to the front and rearbearings 4 and 5 are entirely surrounded by metal in, intimate contactwith the heated liquid in the jackets 63 and 64. The oil` flow to thebearings is sufficiently slow\ that the oil is heated while flowingth-rough the passages to the bearings and reaches the bearings at` thesame temperature as the heating liquid or'the machine at that point. Itis possible that the front and rear bearings may be intentionallymaintained at different temperatures, but the oil temperature at eachbearing is automatically controlled, and the heating of the oil is morepositive since it is done substantially at the point of use' and-is notaffected by outside conditions during transit to the bearings. 'I'hismethod-of heating the oil is less expensive than external heaters whichwould 'also be less positive. I

For convenience, an instrument panel may be mounted in conjunction withthe machine to supportthe oil filter 48, the thermostats 69, and thesight glasses in the oil lines. The heaters IUI and |02 are preferablyconnected with small pilot lights 1| which serve to indicate that theheaters are or are not operating, and which may also be 'mounted uponthe instrument panel 10. There is a pilot light for each heater.` Anoperators light 12 maybe provided on the instrument panel for theoperators convenience. 5

In Figs. 7 and 8'the heating principle is applied to the base of themachine which supports both the work holder and the, tool holdingcarriage, to thereby provide a machine base which will be stable andwill not change position by contraction and expansion due to variationsin temperature caused byany means and thus affect the relative positionsof the work piece and tool. As Ishown in Fig. '1, a work holder ashereinbefore described is mounted on a sub-base or table 13 which is, inturn, mounted on a floor base 1,4. The sub-base or table 13 is shown asbeing a cored, ribbed, box-like member forming a tank for containing`liquid, andhaving therein immer, sion heaters 15, preferably electric,but which may be of any wellknown type. One or a plurality of thermostatbulbs, disposed in either the liquid in the tank formed by the table orsubbase 13 -or in lthe metal going to make up the table or sub-base asthe installation may require, may vbe provided to cooperate withsuitable thermostatic control means for regulating operation of theimmersion heater's 15. Thus, the subi base' or table may be maintainedvat av constant temperature and thereby unaffected as to position bytemperature changeand resultant contraction and expansion. Heatdissipated -to the' 'base 14,to the work holder-.,hereinbefore describedwhich is mounted on the table or sub- Y base orA table 13.

base 1s, and to the cool holder 11, win sem" likewise to maintain theseparts at a constant temperature and eliminate changes in position' vting or assembly thereby eliminating stresses and strains resulting fromsubsequent temperature changes.

In Fig. 81s illustrated another application of the heating `principle.Whereas in Fig. '1,"the means forv heating vthe table or sub-base 13 andthe heating means for the work holder mounted thereon ,areseparate, inthe structure-shown in Fig. 8 the heating means is common to both. Thesub-base or table forms a tank for containing liquid and in which therevare immersion heaters 1l. A conduit 18 leads from the interior of thetank, preferably at one end, toa pump yiii operated by a' motor 8l sothat liquid heated in the tankmay be drawn therefrom bythe pump andforced through a conduit 32 to branch conduits 83 and 8l leading to therespective jackets 63 and 8l about the bearings 4 and 5. The liquid isdrawn out of the jackets 63 and 64 by the pump through conduits 85 and'86 and through a common conduit 81 to and through the tank in thesub-base or table 13 and over the immersion heaters 15 for reheating andrecirculation through the jackets 83 and 64. Suitable thermo- Astaticcontrol means are provided for regulating,

operation of the immersion heaters 'IlY and a water supply reservoir 88maintainsthe ilow circuit continually filled with liquid.

For alternative use when desired, apump' 89 operated by a motor 88a maybe provided which draws dliquidfrom the tank in the sub-base or table 13past a single immersion heaterv 80 in a tank 80a through conduits 9| and92 and forces it through conduits 83, 83 and 84, through the respectiveJackets 63 and 6l, and through conduits 85, 86 and 81 back to the tankin the'sub- The immersion heaters 15 may or may not be utilized asheating means,` and a thermostatio control means including a bulb 94 isprovided in conjunction with the immersion heater 88 for controllingoperation thereof. Continuous pumping of a relatively large volume of Yliquid will result in thev temperature of the liquid returning to thetank 13 being practically the same as the temperature of the liquid atthe outlet of the tank or at the point of entry into the jackets63 and64. 4

It is important that the centers. in the partI being nished have asmooth 'surface and be of the' correct angle to insure the part rotatingv properly and being finished correctly when supported between malecenters on the machine upon which the work is'being done. One method ofgrinding centers has been to move the grinding element straight into thework and theni'eed the wheel laterally across the work untilsparkingindicated that the center had been ground concentric and round.0n completing the grinding operation, some concentric lines or circlesare there by the grinding wheel.

visible on the ground surface, having been' left For the purposeofeliminating such concentric lines or circles, the tool holder 11, rig.6, which is mounted for move- 'ment of the tool spindlel 85 bothparallel and perpen'dicularly to the` center line of the work holder'pended claims.

and work piece is also mounted for movement diagonally tothe center lineof the Work holder and Work piece., As shown in Fig. 8, the hand wheel96 is provided for moving the tool holder v 11 and tool 91 into the workpiece along a line parallel to the longitudinal center line of the workpiece. The hand Wheel '98, Fig. 6, is 'provided for moving the'toolholder 11 and tool 91 perpendicularly to thel work piece center line,both movements of the tool holder 11 being along suitable ways as iswell known in the art. To move the tool holder 11 and tool 91 diagonallyof the longitudinal center line of the work piece, a hand wheel |03,Fig. 6,-is provided for actuating a pinion gear 99 which meshes with arack |100 portionate to that produced byv machine operation andtherebymaintain a substantially uniform temperature .of themachine part at adegree at least equal to the highest degree pron' duced by machineoperation.

2. In a machine. of. the character described wherein heat is developedincident to machine operation, and the temperature of the machine partsfiuctuates in accordance with the degree disposed diagonally to thecenter line of the work .l

holder and work piece, suitable ways being provided for movement of thetool holder andl tool in such direction. TheY temperature control meanshereinbefore described serves to eliminate any change in position ofboth the work piece and tool due \to expansion and contraction of partsinduced by temperature change.

' Controlling the relationship of the various ma'- ing a given settingor adjustment of the-machine units'or parts constant regardless oftemperature changes exteriorly of the machine by controlling temperaturechange within the machine insures uniform accuracy of work produced inthe machine and saves much machine operating time now lost in makingpart contraction and expansioncompensating adjustments temperaturecontrolled.

in machines not Thev principle herein disclosed is applicable to any andall machines where accuracy of work produced is dependent upon therelative position chine units or Darts to each other, and maihtainof apart of the machine or its fixtures tosome v other parts or fixtures,and where'such-relative .position is -susceptible to variation due totemperature change from any cause and resultant contraction or expansionofthe parts or fixtures. From the above description it will beapparentacter described possessing the particular features of advantage beforeenumerated as desirable, but which obviously is susceptible ofmodification in its form, proportions, detail construction and ar.-

I that thereis thus provided av device of the charrangements of partswithout departing from the principle involved or sacrificing; any lo1'its advantages.

Whilein order invention has been described-in language more or lessspecific as to structural features, it is to be understood that theinvention lis not limited to 'to comp1y with `the statute, the

the specific features shown, but' that the means and construction hereindisclosed comprise the preferred form of several modes 'of putting theinvention into eect, and the invention .is therefore claimed in any ofits forms or modifications withinthe legitimate and valid scope of theapthrough which access may lbe had to the work 'of machine operation andlatmospheric influences and conditions, a thermo-syphonic Aoperatingheating' means effective to absorb the temperature fluctuations andmaintain the temperature of the machine uniform to minimize temperatureproduced expansion and contraction of the machine parts and resultingdeviation of operating and work members, a regulator for controllingoperation of the thermo-syphonic operating heating means, and meansassociated with the thermo-syphonic operating heating means effective todeter rapid or violentfiuctuations therein. I 3. The method ofminimizing constructional and expansional change and part displacementin a machine wherein fluctuating degrees of heat are developed incidentto machine operation withv coincident contractional andexpansional`cha1'igev in the relative positions and dimensions of the'jmachine parts, which includes supplying heat to 'the machine partsother than'that developed by machine operation and in degrees converseto the degrees of heat developed by machine operation whereby tomaintain a uniform temperature of the machine parts'.

4. In the art of manufacture and part assemlbly of a machine whereintemperature fluctuations are' produced by machine operation. the methodwhich consists in heating the parts to a temperature'at least equal tothe highest tem- -perature produced by machine operation, andlfinishingand assembling the partswhile at that'.

temperature.

5. In a machine including a rotatable member and bearings therefor, andwherein. rotation of the member relative to the bearings produces a risein the temperature of the member and bearings, a fluid thermo-syphonicoperating supplemental heating means for minimizing temperature producedexpansion and contraction of the member and bearings and resultingdeviation of the member and bearings' by maintaining the temperature ofthe mem-ber and bearings substantially equal to the highest vtemperatureproduced by rotation of the member relative to the bearings', aregulator for the supplemental heating meansand means for maintainingthe supply of heating fluid constant. y 1

6. In a machine assembly of the character described, a frame, spacedbearings therein, a ro'- tatable 'hollow spindle supported in thebearings, a work supporting and locating member within theA spindle, avlateral opening in the spindle supporting and' locating means, and meansfor l minimizing expansion and contraction of the member andlbearingsrand. resulting deviation of the bearings and member includingmeans for supplying heat to the assembly supplemental to heat generatedby and during operation of the :machine or any parts to compensate forfluctuations in such generatedheat and maintain the machine and itsoperating partsat a uniformV I temperature. f

"I. In a machine assembly ofthe character described, a. frame, spacedb'earings'thereinLa rotatable hollow spindle supported-.in thebearings',

a work supporting and locating means within the spindle, a lateralopenings in the spindle through which access may be had to the worksupporting and locating means, a cover for the opening, and

means for minimizing expansion and contraction -thereof and resultingdeviation of operating and work members including means for supplyingheat tothe assembly supplemental to heat generated by and duringoperation of the machine' or any parts and inversely proportionate.thereto to compensate for iluctuations in such includes subjecting theparts to heat from a iluid mediumand independently of the heat gen-`erated by friction between the relatively movable parts, and of a higherdegree than that generated by friction between the relatively movableparts,

. to maintain lthe parts at a temperature higher generated heat andmaintain the machine and l' its operating parts at 'a uniformtemperature'. 8. In a machine assembly of the character described, aframe, spaced bearings therein, a ro` tatable hollow spindle supportedin the bearings, 1

of and resulting'deviation of operating and work 25 members ,includingmeans for supplying heat to the assembly supplemental to heat generatedby and during operation of the machine and inversely proportionatethereto to compensate for uctuations in such generated'heat and main- 30tain themachine and its operating parts at a uniform temperature, andmeans for. controlling the amount and degree of .heat supplied. I

9. In a machine wherein heat is developed incident to machine operation,supplemental heat-4 ing means for minimizing expansion and contractionof the machine parts and resulting deviation of the operating and work-members bycontrolling temperature fluctuations and resultantcontractional and, expansional displacement ofmachine parts, and meansassociated with the supplemental heating means effective to deter rapidor violent' fluctuations in temperature thereof.

10. 'I'he herein described method of minimizing deviation of operatingan/d work members incident to expansion and contraction ofthe parts.

of a machine tool, including the step of subjecting the machine-tosupplemental Vheat supply in versely proportionate to the 'temperaturefluctuations of the machine produced incident to its operationand'finiluence of. atmospheric4 conditions, the procedure being suchthat the temperature of the machine is .maintained substantiallyconstant at a degree at least equal to the highest temperature inducedunder ordinary working conditions.

11. The method of producing a machine tool having parts movingrelatively to each other during machine operation andv therebygenerating heat and producing an increase inA machine temperature, whichincludes assembling the parts into operative relation while at atemperature substantially coincident with the temperature -produced inthe parts by machine operation, and

thereafter supplying supplemental heat to the tool to compensate foriluctuations in such generated heat and maintain the machine and itsoperating parts at a constant temperature at least equal to thetemperature of the machine parts at assembly.

12. The method of operating a machine wherein relatively movable partsare so arrangedwith respect to each other as to produce friction andgenerate heat by their relative movement, which than that induced bysuch `friction.

13. The method of minimizing contractional and expansional partdisplacement and change.

of dimension in a machine wherein fluctuating -degrees of heat aredeveloped incident to machine operation with coincident contractionaland expansional change in the relative positions and dimensions of themachine parts, which vincludes constantly circulating a iluid heatingmedium in effective relation with the machine parts and regulating thetemperature of the circulated nuid heating medium so as to supply adegree of heat which, either supplemented by or independently of theheat developed by machine operation, maintains the machine parts at apreselected temperature. Y i

14. The method of minimizing contractional and expansional partdisplacement and change of dimension in a machine wherein fluctuatingdegrees -of heat are developed incident to machine operation withcoincident Acon'tractional `and expansional change in the relativepositions and dimensions of the machine parts, which includes supplyingsupplemental heatto the machine parts, and regulating the suppliedsupplemental heat withrespect to the degree of heat developed by machineoperation in such manner as to maintain the machine parts at apreselected temperature at least equal to the maximum temperaturedeveloped by machine operation.

15.In a machine assembly wherein tool and work members are movedrelatively to each other for prescribed operation on the work member bythe tool, a frame, bearings in the frame, a rotatable spindlev supportedin the bearings, a work supporting and locating means associated withthe spindle, and means for minimizing temperature produced contractionand expansion ot the assembly parts and resulting deviation of tool andwork members from prescribed position, in-

L cluding means for supplying heat to the'asseming machine operation andinversely proportion bly supplemental to heat generated by and dur'- atethereto to compensate for fluctuations in such generated heat andmaintain the machine assembly at a uniform temperature, and a regulatorfor controllingthe amount and degree of supplemental heat supplied.

16. In a machine assembly wherein tool and work members are movedrelatively to each other for prescribed operation on the work member bythe tool, a frame,'bearings in the frame, a rotatable spindle supportedin. the bearings, a work supporting Aand locating means associated withthe spindle, and means for minimizing temperature produced contractionand expansion of the assembly parts and resulting deviation of t'ool andworkmembers from prescribed position, v

including a- .iluid'thermo-syphonic operating meansfor supplying heat tothe assembly supplemental to heat generated by and during maf ichineoperation and inversely proportionate thereto to compensate forfluctuations in such generated heat and maintain the machine assemblyvvat'a uniform temperature, and a regulator for controlling the amount anddegree of supplemental heat supplied.

- RALPH P. GARRISON.

`JOHN rR. GARRISON.

